Structural framework, petrography and U-Pb zircon ages of dykes intruding granitoids from the 2350 Ma Lagoa Dourada suite ? Mineiro Belt, southeastern Brazil.

A Su?te Lagoa Dourada (SLD), localizada no Cintur?o Mineiro (CM), borda sul do Cr?ton S?o Francisco (CSF), datada em ca. 2,35 Ga, ? composta por biotita-hornblenda tonalitos cortados por uma rede de diques classificados em 5 diferentes tipos (Tipos 1 a 5). Esses tipos foram individualizados a partir de suas rela??es de corte e orienta??o espacial, obtidas com cartografia de 4 ?reas alvos, al?m da composi??o modal e textura. Com caracter?sticas microestruturais majoritariamente ?gneas, a folia??o observada nestes diques foi gerada durante a sua coloca??o, associada ao pr?prio fluxo magm?tico. As rela??es de corte observadas mostram que os diques Tipo 1 (ca. 2347 Ma) s?o os mais antigos, cuja idade obtida superp?e, dentro do erro anal?tico, a idade da rocha hospedeira. Esses diques foram alojados por meio de um sistema de fraturas sin-intrusivas provenientes da contra??o volum?trica do pl?ton durante a sua cristaliza??o. O processo de ruptura da rocha hospedeira para a coloca??o dos demais tipos deve-se provavelmente ao fraturamento provocado pela press?o magm?tica, tendo a intrus?o mais jovem (Tipo 5, ca. 2332 Ma) ocorrido aproximadamente 20 Ma ap?s a sua cristaliza??o. Tem-se ent?o o registro singular da produ??o de crosta em ca. 2350-2330 Ma para a SLD e diques nela intrusivos, tempo que corresponde a um per?odo de car?ncia global do registro de gera??o de crosta continental (2,45 e 2,2 Ga).The Lagoa Dourada Suite (LDS), located in the Mineiro Belt, southern margin of the S?o Francisco Craton, dated at ca. 2.35 Ga, is composed of biotite-hornblende tonalites crosscut by a network of dykes classified into 5 different types (Types 1 to 5). These types were individualized based on their cutting relations and spatial orientation, through the outcrop mapping of 4 workstations, besides the modal composition and texture. With microstructural features mostly igneous, the foliation observed in these dykes was generated during their emplacement, associated with the magmatic flow itself. The observed cutting relations show that Type 1 (ca. 2347 Ma) is the oldest one, whose obtained age overlaps, within the analytical error, the host rock age. It had been emplaced through a system of syn-intrusive fractures resulting from the volumetric contraction of the pluton during its crystallization. The host rock rupture responsible for the emplacement of the other types is probably due to the fracturing caused by the magmatic pressure, with the youngest intrusion (Type 5, ca. 2332 Ma) occurring approximately 20 Ma after its crystallization. Therefore, there is a singular record of the production of crust at ca. 2350-2330 Ma for LDS and intrusive dykes, a time that would correspond to a global paucity period in the continental crust formation (2.45 e 2.2 Ga)